Multi-disc brake pad

ABSTRACT

The present invention relates to a brake pad for rail vehicles, including at least two friction material blocks and at least one holding device. The individual friction material blocks are lamellar in shape and are connected to one another along their longitudinal sides to form a brake pad. The connection is constructed such that the individual friction material blocks may be displaced with respect to one another. The present invention also relates to a rail vehicle brake including at least one brake shoe, a friction material block holding device, a power unit having a carrier body and a connection device connecting the power unit to the at least one brake shoe.

BACKGROUND OF THE INVENTION

The invention relates to a brake pad, particularly for rail vehicles,comprising at least two friction material blocks. The invention alsorelates to a process for manufacturing such a brake pad, and alsorelates to a brake shoe, particularly for rail vehicles having such abrake pad.

Brake pads are used in pad brakes or pad brake units. Pad brakes arebrakes in which a brake cylinder, lever transmission and an adjustingmechanism operate to press a brake pad onto the wheel running surface inorder to achieve a braking effect. With respect to the furtherdevelopment of brake pad units in the case of rail vehicles, referenceis made to “Brakes for Rail Vehicles”, Handbook—Brake-Related Terms andValues, Knorr-Bremse AG München, 2nd Edition, 1990, Page 41.

The brake pads of the prior art are often constructed as a one piecefriction material block. Materials of the brake pads or frictionmaterial blocks are perlitic cast iron with lamellar graphite, plasticmaterial consisting of a mixture of different substances in anartificial resin bond or buna bond, or sintered material which consistsof finest metal powder, such as iron, copper or nonferrous heavy metal.

U.S. Pat. No. 1,219,824, shows a brake pad which comprises a pluralityof friction material blocks which are separated by an elastic layer. Theindividual friction material blocks are mounted transversely to thelongitudinal direction of the brake shoe. As a result of thisarrangement, the brake pad experiences only slight expansion changes inthe event of fluctuating temperatures.

German Patent Document DE 24 18 024 shows a carbon-containing airplanebrake disk consisting of a strong durable center core and brake liningswhich are fastened on both sides and are made of a light-weight materialwhich is subject to wear. The materials which are subject to wear areconnected with the center core by an adhesive layer.

Japanese Patent Document JP 55-97537, shows a brake pad which has aslotted construction in the longitudinal direction for reducing thebraking noise. The reduction of the braking noise because the slottedconstruction allows higher temperatures on the braking area.

German Patent Document DE 30 33 936 shows a brake shoe with severalbrake pads which can be changed very easily.

British Patent Documents GB K 13850 and GB P 14036 show brake padshaving lamellar friction material blocks which are connected on theirlongitudinal sides to form a brake pad. The brake pads were heldtogether by a bolt connections extending transversely to the diskdirection.

With respect to the constructions of brake pads, reference is also made,for example to “Brakes for Rail Vehicles”, Handbook—Brake-Related Termsand Values, Knorr-Bremse AG München, 1990, Pages 22 to 23.

In the case of the above-described pad brake systems according to theprior art, the contact pattern is insufficient because of thermalexpansions and axial displacements. In fact, the contact pattern is thepoorer, the harder the material of the pad. The poor contact patternresults in the formation of corrugations or in cracking in the wheelrunning surfaces and therefore generates considerable noise duringbraking.

It is an object of the invention to provide a brake pad system or acomponent of a brake pad system by means of which the above-mentioneddisadvantages can be overcome.

The brake pad according to the principles of the present inventioncomprises at least two friction material blocks. The individual frictionmaterial blocks are lamellar in shape, and are connected mechanically orby an elastic intermediate layer along their longitudinal sides to forma brake pad. As a result of the elastic intermediate layers between theindividual friction material layers or the mechanical connections, thebraking noise can be reduced because, during the braking, the frictionbetween the individual friction material blocks absorbs noise energy.

Another advantage of the brake pad according to the invention is thefact that, in the case of a non-uniform wear of the wheel tire or duringaxial displacements, the individual disk stacks can shift in thevertical direction and thus adapt themselves to the running surface ofthe wheel, whereby an essentially identical surface pressure is alwaysensured irrespective of the axial position or the wear.

In a preferred embodiment, the elastic intermediate layer is an adhesivelayer. As an alternative, the mechanical connection is a screwed,riveted or form-locking connection, particularly a clamp-typeconnection.

A brake pad comprises at least two, preferably three to four, diskssituated side-by-side. The disks are mechanically or form-lockinglyconnected with one another along the longitudinal side.

In a preferred embodiment, a holding device fastening the frictionmaterial block to a brake shoe is provided for each friction materialblock. In the case of a lamellar construction of the friction materialblocks, each disk has such a holding device on the side facing away fromthe wheel running surface and facing the brake shoe.

Preferably, the holding devices of the individual friction materialblocks have a sheet metal reinforcement with integrated holding angles.The sheet metal reinforcement is non-detachably connected with theindividual friction material block or the disk stacks, for example, bygluing. The sheet metal reinforcement transmits contact pressure forcefrom the brake shoe to the friction material blocks and the contactpressure force is therefore introduced from the brake shoe to the brakepad. The holding angles for fix the brake pad on the brake shoe andprotect against the falling-out or rattling of the individual frictionmaterial blocks.

The holding angles are preferably constructed as U-shaped leaf springswhich are part of the reinforcement arranged on the friction materialblock. The invention also provides a process for producing such abrake-pad. According to the invention, the individual friction materialblocks are obtained by being pressed or cut out of plates and areconnected by gluing or by a mechanically elastic connection to form abrake pad, so that energy can be absorbed by the connection.

The invention also provides a brake shoe having such a brake pad. Thebrake shoe has a carrying body, a connection device to the power unit ofthe pad braking device for operating the brake shoe as well as afriction material block holding device. The friction material blockholding device can be a guide rail which extends in the wheel turningdirection.

The brake shoe according to the invention is exchangeable withconventional brake shoes because the connection of the inventive brakeshoe is analogous to that of the conventional brake shoes.

In order to keep the individual forces of the friction material blocksof the multi-disk brake pad upon the wheel running surface constant, theguide rails may be constructed in the form of a balance beam guide railsystem. The balance beam guide rail system supports a relative verticaldisplacement of the disks of the brake pad. This displacement isperpendicular to the wheel running surface. The balance beam system incombination with the multi-disk brake pad, in which the individual diskscan be displaced in the vertical direction as a result of the mechanicalor shear-elastic intermediate layer, therefore results in a very goodcontact pattern. This measure permits a higher loading capacity of thewheels and reduces the formation of corrugations or cracking and thusthe development of noise when the wheel is rolling.

Furthermore, the balance beam guide rail system is characterized by anelastic yielding perpendicular to the wheel running surface and can beconstructed along the entire curve length of the brake pad in one pieceor divided into several areas. Multiple-slot guide rails are alsoconceivable. Furthermore, the balance beam guide rail system can becomposed of individual balance beams, one balance beam being assigned totwo friction material blocks respectively. The individual balance beamsmay be hinged to one another in a form-locking manner to form thebalance beam system according to the invention.

Alternatively, the entire balance beam system can be produced as anintegrated component, for example, of sectional steel.

In order to ensure that the brake pad will still rest on the wheelrunning surface, during large lateral displacements of the wheel, thebrake shoe laterally has guiding parts toward the wheel face whichpermit a lateral movement of the brake pad. Preferably, these guideparts are constructed as wear-resistant plates toward the wheel side. Inorder to be able to carry along the friction material blocks, which areconnected with the brake shoe by way of the friction material holdingdevice, synchronously during an axial displacement of the wheel set, itis provided in a special embodiment of the invention that the connectingdevice to the power unit is further developed such that it permits sucha movement. A pendulum suspension of the brake shoe is particularlysuitable for this purpose.

Other objects, advantages and novel features of the present inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of a conventional pad brake unit of the prior art.

FIG. 2 is a view of a brake pad according to the invention.

FIG. 2B is a view of a first embodiment of the brake pad of theinvention according to FIG. 2A with a mechanical connection of theindividual friction material blocks.

FIG. 2C is a view of a second embodiment of the invention with mutuallyconnected intermediate layers.

FIG. 3A is a sectional view of the further development according to theinvention of the brake shoe with the brake pad fastened thereto.

FIG. 3B is a sectional view along Line A—A according to FIG. 3A;

FIG. 3C is a view of a one-piece embodiment of the balance beam systemof the brake shoe according to the invention.

FIG. 3D is a view of a first alternative embodiment of a balance beamsuspension according to FIG. 3A.

FIG. 3E is a view of a second alternative embodiment of a balance beamsuspension according to FIG. 3A.

FIG. 3F is a view of a third alternative embodiment of a balance beamsuspension according to FIG. 3A.

FIG. 4A is a cross-sectional view of an embodiment according to theinvention of a brake shoe with a multi-disk brake pad fastened theretoand lateral guide parts.

FIG. 4B is a view of an alternative embodiment with respect to FIG. 4Awith a rubber-elastic suspension.

FIG. C is a view of an alternative embodiment with respect to FIG. 4Bwith a spring-elastic suspension.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a brake pad unit according to the prior art,specifically the pad brake unit PC 7X constructed and supplied byKnorr-Bremse System Für Schienenfahrzeuge GmbH, in a condition in whichthe brake cylinder is bled. It comprises two brake pads 3 fastened tothe brake shoe 1. The brake pads 3 are fastened in the brake shoe 1 by aform-locking connection of the holding devices 5 arranged on each brakepad 3. The operating system for the pad brake unit comprises a piston 7and a brake cylinder which operates the connection device 11 of thebrake shoe 1 by way of levers 9.

Additional details are the pneumatic connection 13 of the brakecylinder, the pressure spring 15, the wear adjuster 17 as well as theadjusting nut 19.

FIG. 2A is a perspective view of an embodiment of a brake pad 3according to the invention. The brake pad 3 according to the inventionis composed of a total of four friction material blocks 20.1, 20.2, 20.3and 20.4. The individual friction material blocks 20.1, 20.2, 20.3, 20.4have a lamellar shape and are connected along their longitudinal sidesto form the brake pad 3 according to the invention. The multi-disk stackis mechanically connected in the embodiment shown in FIG. 2A by means ofsheet metal clamps 22.1, 22.2 for forming a stack. The sheet metalclamps engage in grooves in the respective friction material blocks20.1, 20.4 situated on the edge of the brake pad.

As a result of the mechanical connection by sheet metal clamps 22.1,22.2 the individual friction material blocks 20.1, 20.2, 20.3, 20.4 aredisplaceable with respect to one another, particularly in the verticaldirection, that is, perpendicular to the wheel running surface. Becauseof the displaceability energy is absorbed, the braking noise is reducedand, also in the event of a wear of the wheel running surface or axledisplacements, a uniform surface pressure is achieved.

A holding device 24.1 and 24.2 holds the brake pad 3 on the brake shoe1, and is positioned on each of the individual friction material blocks20.1, 20.2, 20.3 and 20.4. The holding device 24.1, 24.2 of the brakepad 3 according to the invention on the brake shoe 1, in the illustratedembodiment, is already set up for the friction material holding device41 according to the invention illustrated in FIGS. 3a and 4A. Naturally,conventional holding devices can also be used which permit a connectionof the lamellar brake pad 3 according to the invention with aconventional brake shoe 1.

The holding device 24.1, 24.2 on the brake pad 3 coordinated with thefriction material block holding device 41 according to the invention iscomposed of two reinforcing metal sheets 26.1, 26.2 respectively whichhave a holding angle 28.1, 28.2.

Each of the sheet metal reinforcements 26.1, 26.2 is non-detachablyconnected with the respective friction material block 20.1, 20.2, 20.3,20.4, for example, by means of a glued connection. Mechanical screwed orriveted connections are also conceivable.

Any known friction materials currently used for brake pads, such as graycast iron, sintered materials, plastic materials or composite materials,can be used as the materials for the individual lamellar frictionmaterial blocks 20.1, 20.2, 20.3, 20.4. With respect to possiblefriction materials, reference is made to “Brakes for Rail Vehicles”,Handbook—Brake-Related Terms and Values, Knorr-Bremse AG München.

In addition to the embodiment with a mechanical holding of theindividual friction materials blocks, which is shown in FIG. 2B, analternate embodiment, as shown in FIG. 2C, firmly connects theindividual friction material blocks 20.1, 20.2, 20.3 and 20.4 withintermediate layers 29.1, 29.2, 29.3. The intermediate layers 29.1,29.2, 29.3 are elastic layers, for example, adhesive layers made of acorresponding elastic material. Such a layer material may beglued-together sponge rubber. The elastic intermediate layers, in turn,permit the displaceability of the individual disks in the verticaldirection, that is, perpendicular to the wheel running surface, so thata uniform surface pressure is achieved.

Likewise, an embodiment is provided in which the intermediate layers29.1, 29.2 and 29.3 for reducing the wear between the friction materialblocks 20.1, 20.2, 20.3, 20.4 are constructed as a sliding layer foil orsliding layer sheet. The wear by abrasion between the friction materialblocks 20.1, 20.2, 20.3, 20.4 is thereby reduced during relativemovements of the individual friction material blocks.

Layers, sheets or foils made of plastic or aluminum are suitable; thelayer can also be applied as a sprayed layer.

In addition to the illustrated embodiment with four parallel disks,embodiments with two, six, or eight disks are also conceivable, whilethe preferred embodiments do not limit the number of disks per brake pad3.

Since the elastic intermediate layers 29.1, 29.2, 29.3 of the frictionmaterial blocks 20.1, 20.2, 20.3, 20.4 as well as their mechanicalconnection absorb energy by friction, for example, by the illustratedclamps 22.1, 22.2, the required low noise is achieved during thebraking.

FIGS. 3A, 3B and 3C show a particularly low-noise brake shoe 1 accordingto the invention.

FIG. 3A is a cross-sectional view of a brake shoe 1 according to theinvention with a multi-disk brake pad 3 according to the inventionarranged thereon, as described in detail with respect to FIGS. 2A to 2C.

Although a particularly low noise level is achieved in combination withthe multi-disk brake pad 3, conventional brake pads could also bearranged on the brake shoe 1 described in the following, withoutdeviating from the idea of the invention.

The brake shoe 1 according to the invention comprises a carrier body 40.A connection device (not shown) to the power unit of the brake pad unit,such as the brake cylinder 7 according to FIG. 1, is mounted on thecarrier body 40. The connection device can either have a conventionalconstruction or can be constructed in the manner of a pendulumsuspension. The latter is of interest particularly for the furtherdeveloped embodiment of the brake shoe 1 described with respect to FIG.4.

A friction material block holding device 41 is provided on the carrierbody 40 to hold the brake pad 3 in holding devices 24.1, 24.2.

As shown, the friction material holding device 41 comprises a total offour guide rails 42.1, 42.2, 42.3 as well as 42.4 which extend in thewheel turning direction. The guide rails 42.1, 42.2, 42.3, 42.4 areconnected with the carrier body 40 by a balance beam system 44. Incombination with the balance beam system 44, the guide rails 42.1, 42.2,42.3, 42.4 permit a displacement of the individual lamellar frictionmaterial blocks 20.1, 20.2, 20.3, 20.4 which form the brake pad 3. Thisdisplacement is perpendicular to the wheel running surface, so that theindividual forces can be kept constant.

As shown in FIGS. 2A-2C, the holding angles 28.1, 28.2 or the u-shapedleaf springs which are part of the disk reinforcement prevent theindividual function material blocks 20.1, 20.2, 20.3, 20.4 from fallingout or rattling.

The further development of the friction material holding device 41 bymeans of guide rails 42.1, 42.2, 42.3, 42.4, by means of the balancebeam system, permits a displacement in the circumferential direction inaddition to the movement of the friction material blocks 20.1, 20.2,20,3, 20.4 perpendicular to the wheel running surface. Thedisplaceability in the circumferential direction facilitates themounting of each friction material block 20.1, 20.2, 20,3, 20,4.

As a result of the friction material block holding device 41 accordingto the invention in combination with the holding device (24.1, 24.2)arranged on the brake pad 3 according to the invention, a movement ofthe multi-disk brake pad can therefore be carried out in the directionof the wheel running surface in order to adapt to the wheel runningsurface. In a combined overall effect with the balance beam system 44,this leads to an unexpectedly low noise level and to a very good contactpattern also, for example, in the event of axial displacements. Inaddition, the capacity of the pad brake is improved by a higherresistance to thermal stress.

FIG. 3B shows the brake shoe 1 and the brake pad 3 along theintersection A—A in FIG. 3A. Identical components as those of FIG. 3Aare characterized by the same reference numbers. The friction materialblock 20.3 is held by the guide rail 42.3 in combination with theholding device] (not shown) and the balance beam system 44. Stops 46 onthe guide rails of the respective multi-disk brake pad preventsliding-out of the friction material block 20.3 in the circumferentialdirection. Instead of a stop 46, a locking closure (not shown) can beused. The guide rail 42.3 illustrated in FIG. 3B is constructed in onepiece along the entire curve length. In an alternative embodiment, whichis not shown in this case, guide rails could be implemented only inpartial areas or multiple-slot guide rails can be implemented. As aresult of their bending-elastic construction, an articulated connectionof the balance beams 48.1 and 48.2 is obtained to the balance beam48.3., as described in the following.

FIG. 3C shows the balance beam system of the friction material blockholding device 41 of the brake shoe according to the invention. Asclearly illustrated, the balance beam system 44 consists of individualbalance beams 48.1, 48.2 and 48.3. The individual balance beams 48.1,48.2, 48.3 can be connected with one another either mechanically bymeans of rivets, screws, weld points or form closure. Additionally, theymay be constructed in one piece of sectional steel.

Corresponding to the number of holding devices on the multi-disk brakestack, the balance beam system consists of one or several individualbalance beams.

FIGS. 3D-3F show embodiments in which the balance beam system 44comprises two balance beams 48.1, 48.2. Identical components as in thepreceding figures have the same reference numbers.

In the embodiment according to FIG. 3D, the balance beams 48.1, 48.2 arefastened in recesses 47.1, 47.2, 47.3 of the three friction materialblocks 20.1, 20.2, 20.3. The balance beam system 44 is fastened on thecarrier body 40 by a pin 49.

FIG. 3E shows an alternative embodiment to FIG. 3D.

As shown in FIG. 3F, the brake pad 3 or the individual friction materialelements 20.1, 20.2, 20.3 may be held by means of reinforcement sheets26.1, 26.2 which, in turn, have holding angles 28.1, 28.4, asillustrated particularly in FIG. 2A.

In a further developed embodiment of the invention illustrated in FIG.4A, the brake shoe 1 is constructed with lateral guiding surfaces 58, 60for large lateral movements of the wheel set. Components identical tothose of the preceding figures have the same reference numbers in FIG.4.

FIG. 4A is a cross-sectional view of the system according to theinvention as well as the wheel 50 to be braked with the wheel runningsurface 52. Guiding surfaces 58, 60 are constructed on the carrier body40 of the brake shoe 1 in the direction of the wheel faces 54, 56. In apreferred embodiment, the guiding surfaces 58, 60 have wear-resistantplates 62, 64. The guiding surfaces 58, 60 act as lateral guiding partsto ensure that, in the event of large lateral displacements of the wheel50, the brake pad 3 remains on the wheel running surface 52 when theentire unit, namely the brake shoe 1 and the brake pad 3, follows thelateral movement. The individual friction material blocks as well as thebalance beam system 44 according to the invention of the frictionmaterial block holding device 42 are clearly visible.

In order to permit the moving-along of the brake shoe 1 during a lateraldisplacement of the wheel 50, the connection device 11 to the operatingdevice must be designed correspondingly, for example, in the form of apendulum suspension.

In addition to the suspension by means of a balance beam system 44, asan alternative and as illustrated in FIGS. 4B and 4C, a movablesuspension of the brake pad 3 with an elastic mat 70 or a corrugatedspring steel sheet 72 can be provided. The construction according toFIG. 4C with a corrugated spring steel sheet 72 has the advantage that abiasing effect as well as a balance beam effect is achieved.

The embodiment according to the invention of a lamellar brake pad incombination with the balance beam suspension, an elastic suspension or aspring steel sheet suspension permits a simple mounting of the brake padsimilar to the known brake lining fastening in the case of disk brakelinings by means of so-called dovetail guides.

Furthermore, a particularly low noise level is achieved during thebraking if the elastic intermediate layers of the friction materialblocks or disks or the mechanical clamp-type connections absorb energyas a result of the friction between the disks. The horizontaldisplaceability of the individual friction material blocks permits anoptimal adaptation to the wheel running surfaces, for example, in theevent of wear because of an axial displacement. The result is a goodcontact pattern irrespective of the operating conditions. The goodcontact pattern reduces the forming of corrugations and cracks thatgenerate noise during the rolling of the wheel.

Furthermore, the lateral guiding elements permit a secure contact on thewheel running surface in the event of large axial movements of the wheelset, and prevent a moving-out from the area of the brake pad.

What is claimed is:
 1. A rail vehicle brake, comprising: at least one brake shoe; a power unit for operating the at least one brake shoe, the at least one brake shoe including a carrier body and a connection device connecting the power unit for operating the brake shoe to the at least one brake shoe, and a friction material block holding device for holding at least one brake pad on the brake shoe, the holding device having at least two guide rails, in a turning direction of a wheel of the rail vehicle, connected with one another by a balance beam system having individual balance beams hinged to one another, and the brake pad having at least two friction material blocks connected to one another at longitudinal edges.
 2. A rail vehicle brake according to claim 1 wherein the brake shoe has lateral surfaces extending toward the face of the wheel.
 3. A rail vehicle brake according to claim 2 wherein the connection device connecting the brake shoe to the power unit is further developed such that, during axial movements of the wheel set, the brake shoe is guided by the lateral surfaces.
 4. A rail vehicle brake according to claim 3, wherein the connection device comprises a pendulum suspension.
 5. A rail vehicle brake according to claim 2, wherein the lateral surfaces are wear-resistant plates facing toward the wheel side.
 6. A rail vehicle brake according to claim 1, wherein the entire balance beam system is an integrated bending-elastic component.
 7. A rail vehicle brake according to claim 6, wherein the integrated component is made of sectional steel.
 8. A rail vehicle brake according to claim 1, wherein the friction material block holding device has at least one spring element, and displaceably guides the at least one frictional material block on the brake shoe.
 9. A brake shoe according to claim 8, wherein the friction material block is biased by the spring element in an operating direction.
 10. The rail vehicle brake according to claim 1, wherein the connection device is a pendulum suspension.
 11. A brake pad for rail vehicles, comprising: at least two friction material blocks having longitudinal sides; at least one holding device mounted on the friction material blocks for fastening the friction material blocks to a brake shoe; wherein the individual friction material blocks are lamellar in shape, and are connected with one another along the longitudinal sides by one of a mechanical connection and a shear elastic intermediate layer to form a brake pad, the shear elastic intermediate layer being one of a sliding layer, a sliding metal sheet and a sliding foil; and wherein the connection is constructed such that the individual friction material blocks may be displaced with respect to one another.
 12. A brake pad according to claim 11, further comprising a holding device assigned to each friction material block.
 13. A brake pad according to claim 12, wherein the holding device is a sheet metal reinforcement facing the brake shoe and has holding angles.
 14. A brake pad according to claim 11, wherein the shear-elastic intermediate layer connection is one of an adhesive layer or an intermediate layer glued to the friction material blocks.
 15. A brake pad according to claim 11, wherein the mechanical connection is one of a screwed, riveted or form-locking clamp-type connection.
 16. A brake shoe for engaging a wheel of rail vehicles, comprising: a carrier body; a connection device connecting a power unit for operating the brake shoe; a friction material holding device for holding at least one brake pad on the brake shoe, the brake pad comprising at least two friction material blocks connected to one another at longitudinal edges; wherein the friction material block holding device comprises at least two guide rails in the turning direction of the wheel, the at least two guide rails connected with one another by a balance beam system and adapted to permit a displacement of the individual friction material blocks perpendicular to a running surface of the wheel so that individual forces can be kept constant.
 17. The brake shoe of claim 16, wherein the connection device is a pendulum suspension.
 18. A brake pad for rail vehicles, comprising: at least two friction material blocks having longitudinal sides; a separate holding device assigned to each friction material block; wherein, the individual friction material blocks are lamellar in shape, and are connected with one another along the longitudinal sides by one of a mechanical connection or a shear-elastic intermediate layer to form a brake pad. 